The present invention relates to a surgical instrument for minimally invasive surgery and in particular an instrument in the form of a pair of pincers or forceps.
Surgical instruments of this kind are used for minimally invasive surgery in order, for example, to grasp tissue, small blood vessels and similar biological materials. Like a pair of pincers or forceps, such an instrument comprises movable gripping elements that can be brought together or spread apart, i.e. closed by movement in a gripping direction or opened by movement in the opposite direction. Because of their small dimensions, the instruments can preferentially be used in the working channel of an endoscope.
The German patent DE 195 37 320 A1 discloses an apparatus for actuating a gripping device for minimally invasive surgery, in which the device resembles forceps in having two movable gripping elements, each in the form of one member of a pair of forceps. The gripping elements are connected to a first and a second holder element, respectively, in each case by way of two flexible connecting elements. In order to spread the two movable manipulation elements apart, or to bring them together, the two holder elements are displaced with respect to one another. An advantage of this apparatus is stated to be that on one hand it comprises no joints that would be subject to wear and tear, while on the other hand it can be manufactured from a single blank of material.
However, this specification does not provide for the said apparatus to be used in minimally invasive surgery in order to coagulate biological tissue, for instance as a bipolar instrument.
In DE 40 32 471 C2 is disclosed an electrosurgical apparatus that can be used either for bipolar coagulation or for separating tissues, as desired, and which comprises three mutually insulated contact rods mounted in an elongated instrument casing. Two of the contact rods have free ends that serve as coagulation electrodes, while the third contact rod acts a cutting electrode. For this purpose the third contact rod can be moved towards the two coagulation electrodes or through these electrodes, so that tissue that is to be coagulated or cut can be clamped between the electrodes as though in a pair of forceps.
DE 39 17 328 C2 discloses a bipolar coagulation instrument with two mutually insulated and movable mouth elements that together form a pair of forceps. In this case a first mouth element is fixed and the second mouth element can be moved with respect to the first mouth element.
Both of the instruments or apparatuses mentioned above are relatively elaborate in construction and hence are correspondingly expensive to manufacture.
The object of the present invention is to provide a surgical instrument, in particular pincers or forceps for minimally invasive surgery, that has a simple structure and as a result can be constructed with a very small diameter.
According to the present invention there is provided a surgical instrument for minimally invasive surgery comprising at least two gripping elements, that can be moved in the manner of forceps towards one another in a gripping direction for the purpose of gripping and apart from one another in an opposite direction, at least one of the gripping elements comprising at one end thereof a first limb and a second limb, which limbs are spaced from one another in the gripping direction and which limbs each comprise at least one flexible region; and a guide sleeve in which at least the first limb of said one gripping element is disposed and can be moved in a longitudinal direction of the guide sleeve relative to the second limb of said one gripping element in such a way that during a relative movement of the first and second limbs with respect to one another said one gripping element is moved in the gripping direction.
It will be appreciated that the limbs bend at their flexible regions when the two limbs of a given gripping element are shifted relative to one another. In principle the instrument is also suitable for use as scissors, when the gripping elements are provided with cutting blades. For example, one edge of at least one gripping element can be sharpened for cutting.
In a preferred embodiment, so that the gripping elements can be moved apart from one another the first limb, for example, of each gripping element is moved in the longitudinal direction of the guide sleeve, towards the gripping end of the gripping element. Because of the torque thus produced, the limbs bend in their flexible region in such a way that the gripping elements are spread apart, moving in the direction opposite to the gripping direction. When the first limbs are moved back, the gripping elements again fold together because of the restoring force of the flexible regions or a corresponding oppositely directed movement of the limbs, as a result of which tissue situated between the gripping elements can be securely grasped. On the whole the instrument is of simple construction, which allows its size to be made particularly small.
In a preferred embodiment, the gripping elements themselves are made of a conductive material, in particular a metal and preferably stainless steel. The gripping elements are preferably so disposed that the limbs do not touch one another and hence are electrically isolated from one another. As a result, the gripping elements are suitable for use as electrodes for the coagulation of biological tissue.
Preferably, each gripping element including both of its limbs is produced as an integral component made of a conductive, in particular metallic material. As a result the gripping elements can be very inexpensively manufactured; it is also possible to make them of conductive plastic or similar conductive materials.
Preferably, the first limb of each gripping element is longer than the second limb, so that the gripping elements can be actuated directly by way of the first limb, i.e. without joints, connecting rods, shafts or similar devices, and with no play whatsoever. In addition, the first limbs can be used directly as conductors of a current for HF coagulation. As a means of actuating the gripping elements, for example, a rod can be welded to the first limb of each element. This enables the actuation to be done at a great distance from the gripping elements.
A further simplification in production of the instrument is achieved in a preferred embodiment by fixing the second limb of each gripping element firmly, in particular to the internal wall of the guide sleeve, for example by a form-fitting connection. Such a design is less expensive in terms of manufacturing technology and requires less space than a screw connection.
In order to supply a high-frequency coagulation current to a tissue grasped by the instrument, the limbs of the various gripping elements are electrically insulated from one another, and in particular are enclosed in an insulating sheath. So that short-circuits are reliably avoided, the limbs of the gripping elements are preferably enclosed in an insulating sheath before installation in the guide sleeve. With such insulation there is no longer any need to be concerned with production tolerances, as a result of which limbs of different gripping elements might come into contact with one another.
For manipulation of the instrument, the guide sleeve is partially inserted into one end of a flexible or in particular metallic tube. The tube can be made in particular of stainless steel corresponding to the types of stainless steel employed in surgery. A flexible or rigid tube facilitates manipulation of the instrument and above all provides good protection against contamination with dirt, and can be more easily cleaned and sterilized for surgical interventions.
Preferably the flexible or rigid tube is provided at the end opposite the guide sleeve with a controllable actuator or a handle to manipulate the instrument, in particular to actuate the gripping elements, i.e. to move them apart from one another or bring them together. The handle enables the surgical instrument to be simply and conveniently manipulated by an operator.
In a further embodiment of the handle the first limbs of the gripping elements are connected to an actuator disposed in the handle in such a way that when the actuator is pushed into the handle, the first limbs are moved away from the handle in the longitudinal direction of the guide sleeve and the flexible or rigid tube, as a result of which the gripping elements move apart from one another, in the direction opposite to the gripping direction. Conversely, the gripping elements move back together, in the gripping direction, when the actuator is moved or pulled out of the handle and hence the first limbs are pulled back again.
Between actuator and handle a spring is preferably disposed, so that with no need for the action of external force the actuator is pressed out of the handle and the gripping elements are brought together; this corresponds, so to speak, to the resting position of the instrument. Then in order to grasp tissue an operator must merely press the actuator into the handle, so that the gripping elements are spread apart, and when they have enclosed the tissue the actuator is released again, whereupon it is pressed back into its starting position by the force of a spring, so that the gripping elements come together and grip the tissue firmly with a specific force.
For use as a bipolar instrument for HF coagulation, in a preferred embodiment the first limb of a first gripping element can be connected to a first connector of a HF current generator and the first limb of a second gripping element, to a second connector thereof. The first and the second gripping elements then correspond to two electrodes of opposite polarity, and they serve to conduct HF current to a tissue that is grasped by both gripping elements.
The invention further relates to the use of the instrument in an endoscope. For this purpose the instrument is preferably movably disposed in the working channel of the endoscope and can be moved out of the endoscope in order to grasp, cut, spread apart and/or coagulate tissue, during which processes the endoscope allows the operator to monitor the instrument visually.
The invention will now be described by way of example with reference to the accompanying drawings.